The Effect of Enzymatic Treatment on the Physical Properties of Blueberries and the Course of the Freeze-Drying Process

This study aimed to determine the effect of enzymatic pre-treatment on the selected physical properties and freeze-drying kinetics of blueberries. Fresh fruits were treated with commercial pectinolytic and cellulolytic enzyme preparations for different durations (20–60 min). The influence of enzyme type and treatment time on water content, water activity, colour, mechanical properties, and drying kinetics was evaluated. The enzymatic treatment decreased the mechanical resistance of the fruits, but the colour changes were generally minor. The freeze-drying time for fresh fruits was significantly reduced from 2855 min to 845–1190 min with enzymatic pre-treatment. The extent of this reduction depended on the enzyme type used and the duration of the treatment. Pectinolytic enzymes were found to be more effective than cellulolytic enzymes in reducing drying time. It can be concluded that using pectinolytic enzymes for 30 min significantly reduced the drying time by a factor of three. Additionally, this process improved the fruit’s physical properties compared to fresh-dried blueberries.